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Fragmentation of numerical algorithms for parallel subroutines library

JOURNAL OF SUPERCOMPUTING 2011年第2期57卷 161-171页

作者： Kireev, S. Malyshkin, V. Russian Acad Sci Inst Computat Math & Math Geophys Siberian Branch Novosibirsk Russia

Fragmentation is a well-known method of the parallelization of numerical algorithms and programs. Algorithm fragmentation allows creating fragmented parallel programs that can be executed on parallel computers of different types (multiprocessors and/or multicomputers) and can be dynamically tuned to all the available resources. Fragmentation of the often used numerical algorithms, their representation for inclusion into the library of parallel numerical subroutines and properties of the runtime system are considered.

关键词： asynchronous programming Parallel program Numerical algorithm Fragment-based programming Dynamic programs' properties

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Automatic Task-Based Code Generation for High Performance Domain Specific Embedded Language

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INTERNATIONAL JOURNAL OF PARALLEL programming 2016年第3期44卷 449-465页

作者： Tan, Antoine Tran Falcou, Joel Etiemble, Daniel Kaiser, Hartmut Univ Paris 11 INRIA LRI Orsay France Louisiana State Univ CCT Baton Rouge LA 70803 USA

Providing high level tools for parallel programming while sustaining a high level of performance has been a challenge that techniques like Domain Specific Embedded Languages try to solve. In previous works, we investigated the design of such a DSEL-NT-providing a Matlab -like syntax for parallel numerical computations inside a C++ library. In this paper, we show how NT has been redesigned for shared memory systems in an extensible and portable way. The new NT design relies on a tiered Parallel Skeleton system built using asynchronous task management and automatic compile-time taskification of user level code. We describe how this system can operate various shared memory runtimes and evaluate the design by using two benchmarks implementing linear algebra algorithms.

关键词： C plus Parallel skeletons asynchronous programming Generative programming

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NetStar: A Future/Promise Framework for asynchronous Network Functions

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2019年第3期37卷 600-612页

作者： Duan, Jingpu Yi, Xiaodong Wang, Junjie Wu, Chuan Le, Franck Southern Univ Sci & Technol SUSTech Inst Future Networks Shenzhen 518005 Peoples R China Peng Cheng Lab PCL Res Ctr Networks & Commun Shenzhen 518005 Peoples R China Univ Hong Kong Dept Comp Sci Hong Kong Peoples R China IBM TJ Watson Res Ctr Yorktown Hts NY 10598 USA

Network functions (NFs) are more than simple packet processors that apply various transformations to the packet content. Modern NFs often resort to various external services to achieve their purposes, e. g., storing flow states in an external storage or looking up a DNS. Working with external services is usually implemented using callback-based asynchronous programming, which is complex and error-prone. This paper proposes NetStar, a new NF programming frame-work that brings the future/promise abstraction to the NF dataplane for flow processing. NetStar simplifies asynchronous NF programming via a carefully designed async-flow interface that exploits the future/promise paradigm by chaining multiple continuation functions for asynchronous operations handling. The programs implemented using the NetStar framework mimic simple synchronous programming but are able to achieve full flow processing asynchrony. We have used NetStar to implement a number of representative NFs. Our experience and evaluation results show that NetStar can effectively simplify asynchronous NF programming by substantially reducing the lines of code, while still approaching line-rate packet processing speeds.

关键词： NFV asynchronous programming future/promise paradigm high-performance software dataplane

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Typing and semantics of asynchronous arrows in JavaScript

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SCIENCE OF COMPUTER programming 2017年 141卷 1-39页

作者： Fritz, Eric Zhao, Tian Univ Wisconsin Milwaukee WI 53201 USA

asynchronous programs in JavaScript using callbacks and promises are difficult to write correctly. Many programs have subtle errors due to the unwanted interaction of event handlers. To fix such errors, the programmer is burdened with explicit registration and de-registration of event handlers. This produces fragile code which is difficult to read and maintain. Arrows, a generalization of monads, are an elegant solution to asynchronous program composition. In this paper, we present the semantics of an arrow-based DSL in JavaScript which can encode asynchronous programs as a state machine where edge transitions are triggered by external events. To ensure that arrows are composed correctly, we provide an optional type checker that reports errors before the machine begins execution. (C) 2017 Elsevier B.V. All rights reserved.

关键词： JavaScript asynchronous programming Type inference Type checking Semantics

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The Early History of F#

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PROCEEDINGS OF THE ACM ON programming LANGUAGES-PACMPL 2020年第HOPL期4卷 1–58页

作者： Syme, Don Microsoft London England

This paper describes the genesis and early history of the F# programming language. I start with the origins of strongly-typed functional programming (FP) in the 1970s, 80s and 90s. During the same period, Microsoft was founded and grew to dominate the software industry. In 1997, as a response to Java, Microsoft initiated internal projects which eventually became *** programming framework and the C# language. From 1997 the worlds of academic functional programming and industry combined at Microsoft Research, Cambridge. The researchers engaged with the company through Project 7, the initial effort to bring multiple languages ***, leading to the initiation *** Generics in 1998 and F# in 2002. F# was one of several responses by advocates of strongly-typed functional programming to the lobject-oriented tidal wavez of the mid-1990s. The development of the core features of F# 1.0 happened from 2004-2007, and I describe the decision-making process that led to the lproductizationz of F# by Microsoft in 2007-10 and the release of F# 2.0. The origins of F#'s characteristic features are covered: object programming, quotations, statically resolved type parameters, active patterns, computation expressions, async, units-of-measure and type providers. I describe key developments in F# since 2010, including F# 3.0-4.5, and its evolution as an open source, cross-platform language with multiple delivery channels. I conclude by examining some uses of F# and the influence F# has had on other languages so far.

关键词： programming Languages Functional programming Object-oriented programming Pattern Matching asynchronous programming Type Providers Units of Measure Dimensions F#

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Automatic Migration from Synchronous to asynchronous JavaScript APIs

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PROCEEDINGS OF THE ACM ON programming LANGUAGES-PACMPL 2021年第OOPSLA期5卷 1–27页

作者： Gokhale, Satyajit Turcotte, Alexi Tip, Frank Northeastern Univ Boston MA 02115 USA

The JavaScript ecosystem provides equivalent synchronous and asynchronous Application programming Interfaces (APIs) for many commonly used I/O operations. Synchronous APIs involve straightforward sequential control flow that makes them easy to use and understand, but their "blocking" behavior may result in poor responsiveness or performance. asynchronous APIs impose a higher syntactic burden that relies on callbacks, promises, and higher-order functions. On the other hand, their nonblocking behavior enables applications to scale better and remain responsive while I/O requests are being processed. While it is generally understood that asynchronous APIs have better performance characteristics, many applications still rely on synchronous APIs. In this paper, we present a refactoring technique for assisting programmers with the migration from synchronous to asynchronous APIs. The technique relies on static analysis to determine where calls to synchronous API functions can be replaced with their asynchronous counterparts, relying on JavaScript's async/await feature to minimize disruption to the source code. Since the static analysis is potentially unsound, the proposed refactorings are presented as suggestions that must be reviewed and confirmed by the programmer. The technique was implemented in a tool named Desynchronizer. In an empirical evaluation on 12 subject applications containing 316 synchronous API calls, Desynchronizer identified 256 of these as candidates for refactoring. Of these candidates, 244 were transformed successfully, and only 12 resulted in behavioral changes. Further inspection of these cases revealed that the majority of these issues can be attributed to unsoundness in the call graph.

关键词： Refactoring JavaScript Static Analysis asynchronous programming

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Transfinite Step-Indexing for Termination

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PROCEEDINGS OF THE ACM ON programming LANGUAGES-PACMPL 2021年第POPL期5卷 1–29页

作者： Spies, Simon Krishnaswami, Neel Dreyer, Derek MPI SWS Saarland Informat Campus Saarbrucken Germany Saarland Univ Saarland Informat Campus Saarbrucken Germany Univ Cambridge Cambridge England

Step-indexed logical relations are an extremely useful technique for building operational-semantics-based models and program logics for realistic, richly-typed programming languages. They have proven to be indispensable for modeling features like higher-order state, which many languages support but which were difficult to accommodate using traditional denotational models. However, the conventional wisdom is that, because they only support reasoning about finite traces of computation, (unary) step-indexed models are only good for proving safety properties like "well-typed programs don't go wrongz. There has consequently been very little work on using step-indexing to establish liveness properties, in particular termination. In this paper, we show that step-indexing can in fact be used to prove termination of well-typed programs-even in the presence of dynamically-allocated, shared, mutable, higher-order state-so long as one's type system enforces disciplined use of such state. Specifically, we consider a language with asynchronous channels, inspired by promises in JavaScript, in which higher-order state is used to implement communication, and linearity is used to ensure termination. The key to our approach is to generalize from natural number step-indexing to transfinite step-indexing, which enables us to compute termination bounds for program expressions in a compositional way. Although transfinite step-indexing has been proposed previously, we are the first to apply this technique to reasoning about termination in the presence of higher-order state.

关键词： termination transfinite step-indexing higher-order state linear types ordinals channels asynchronous computation asynchronous programming logical relations

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A Concurrency Model for JavaScript with Cooperative Cancellation 14

A Concurrency Model for JavaScript with Cooperative Cancella...

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14th International Conference on Software Language Engineering (SLE)

作者： Zhao, Tian Li, Yonglun Univ Wisconsin Milwaukee Milwaukee WI 53211 USA

ISBN: (纸本)9781450391115

This paper proposes a concurrency model for JavaScript with thread-like abstractions and cooperative cancellation. JavaScript uses an event-driven model, where an active computation runs until it completes or blocks for an event while concurrent computations wait for other events as callbacks. With the introduction of Promises, the control flow of callbacks can be written in a more direct style. However, the event-based model is still a source of confusion with regard to execution order, race conditions, and termination. The thread model is a familiar concept to programmers and can help reduce concurrency errors in JavaScript programs. This work is a library-based design, which uses an abstraction based on the reader monad to pass a thread ID through a thread's computation. A thread can be cancelled, paused, and resumed with its thread ID. This design allows hierarchical cancellation where a child thread is cancelled if its parent is cancelled. It also defines synchronization primitives to protect shared states. A formal semantics is included to give a precise definition of the proposed model.

关键词： asynchronous programming thread JavaScript

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Improving Scalability of Web Applications by Utilizing asynchronous I/O 8th

Improving Scalability of Web Applications by Utilizing Async...

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ICT Innovations Conference on Cognitive Functions and Next Generation ICT Systems

作者： Rankovski, Gjorgji Chorbev, Ivan Univ Ss Cyril & Methodius Fac Comp Sci & Engn Rugjer Boskovikj 16POB 393 Skopje 1000 Macedonia

ISBN: (纸本)9783319688558;9783319688541

The focus of the paper is the use of asynchronous I/O calls in web applications to improve their scalability, by increasing the number of requests per second that it can process and decreasing the average response time of the system. Popular development frameworks have always included only blocking I/O APIs in their base, making asynchronous I/O methods hard to implement and maintain. Significant effort has been made in recent years to enrich these frameworks with better syntax for asynchronous API to improve developers' experience and encourage its use. Such improvement in .NET's syntax is put to the test in this paper and the results are presented and evaluated.

关键词： Distributed system Web application Web service asynchronous programming I/O Load test

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Nessie: Automatically Testing JavaScript APIs with asynchronous Callbacks 22

Nessie: Automatically Testing JavaScript APIs with Asynchron...

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ACM/IEEE 44th International Conference on Software Engineering (ICSE)

作者： Arteca, Ellen Harner, Sebastian Pradel, Michael Tip, Frank Northeastern Univ Boston MA 02115 USA Univ Stuttgart Stuttgart Germany

ISBN: (纸本)9781450392211

Previous algorithms for feedback-directed unit test generation iteratively create sequences of API calls by executing partial tests and by adding new API calls at the end of the test. These algorithms are challenged by a popular class of APIs: higher-order functions that receive callback arguments, which often are invoked asynchronously. Existing test generators cannot effectively test such APIs because they only sequence API calls, but do not nest one call into the callback function of another. This paper presents Nessie, the first feedback-directed unit test generator that supports nesting of API calls and that tests asynchronous callbacks. Nesting API calls enables a test to use values produced by an API that are available only once a callback has been invoked, and is often necessary to ensure that methods are invoked in a specific order. The core contributions of our approach are a tree-based representation of unit tests with callbacks and a novel algorithm to iteratively generate such tests in a feedback-directed manner. We evaluate our approach on ten popular JavaScript libraries with both asynchronous and synchronous callbacks. The results show that, in a comparison with LambdaTester, a state of the art test generation technique that only considers sequencing of method calls, Nessie finds more behavioral differences and achieves slightly higher coverage. Notably, Nessie needs to generate significantly fewer tests to achieve and exceed the coverage achieved by the state of the art.

关键词： asynchronous programming test generation JavaScript testing

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